Typically topical, otic, or ophthalmic products containing water insoluble steroid(s) alone or in combination with antimicrobial agent(s) are very greasy because of mineral oil or petrolatum present in the suspension. Such products are very hard to instill and spread into the ear canal or skin folds, especially on haired areas. In the case of otic application, the “oily residue” stays in the ear canal after application for prolonged periods of time, which is not desirable.
There are some aqueous suspensions (for example, Lotemax Suspension, for ophthalmic use) or oil-in-water lotion products for topical use. However, many of these products still leave non-drug residues because of high concentrations of suspending agents (0.2% w/w for example), surfactants (2-5% w/w) and/or oily components (2-10% w/w) which may cause harmful effects. The ideal topical, otic, or ophthalmic formulation should be low in residues, isotonic, aqueous based, and physically and chemically stable.
In U.S. Pat. No. 5,540,930, the non-ionic polymer concentration in its steroid composition is about 0.2-2% w/w and the claimed molar concentration range for the steroid:non-ionic-polymer:surfactant is between about 1:20:1 and about 1:0.01:0.5. U.S. Pat. No. 5,540,930 indicates that the polymer used in the formulation has to be non-ionic.
A reduction in amount of polymer and surfactant used in a steroid composition should be beneficial to the biological membrane. Thus, there exists a need for aqueous suspensions of water insoluble corticosteroids, which are free of problems of prior art formulations which can be easily applied.